#include<stdio.h>
int main()
{
	int i = 0;
	int n = 0;
	scanf_s("%d",&n);
	int t = n / 4;
	int sum = 0;
	for (i = t; i > 0; i--)
	{
		sum += i;
	}
	printf("%d", sum);
	return 0;
}